WO2014083994A1 - Packet transfer control system and method - Google Patents

Packet transfer control system and method Download PDF

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Publication number
WO2014083994A1
WO2014083994A1 PCT/JP2013/079329 JP2013079329W WO2014083994A1 WO 2014083994 A1 WO2014083994 A1 WO 2014083994A1 JP 2013079329 W JP2013079329 W JP 2013079329W WO 2014083994 A1 WO2014083994 A1 WO 2014083994A1
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Prior art keywords
packet
transfer control
packet transfer
congestion
qos
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PCT/JP2013/079329
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French (fr)
Japanese (ja)
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一範 小澤
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日本電気株式会社
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Priority to JP2012-262972 priority
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Publication of WO2014083994A1 publication Critical patent/WO2014083994A1/en

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    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L47/00Traffic regulation in packet switching networks
    • H04L47/10Flow control or congestion control
    • H04L47/24Flow control or congestion control depending on the type of traffic, e.g. priority or quality of service [QoS]
    • H04L47/2416Real time traffic
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04WWIRELESS COMMUNICATION NETWORKS
    • H04W28/00Network traffic or resource management
    • H04W28/02Traffic management, e.g. flow control or congestion control
    • H04W28/0289Congestion control

Abstract

A packet transfer control system and method whereby, when transferring packets, the bit rate for packets carrying audio or video is changed if congestion is detected.

Description

Packet transfer control system and method

The present invention relates to a communication system that performs packet transfer while controlling communication quality for each packet.

In recent years, the capacity and speed of mobile networks have been increased, and systems such as LTE (Long Term Evolution) and EPC (Evolved Packet Core) have begun to be introduced. In systems prior to LTE and EPC, circuit switching for voice calls and videophone calls and packet switching for sending data were made up of separate systems, but in LTE / EPC systems, voice call data was placed on the same packet communication path. And TV phone data, content distribution data, and so on and so-called data signals (application data, document data, photo data, etc.) flow together. Furthermore, as mobile terminals, not only conventional so-called Galapagos mobile phones but also so-called smart devices such as smartphones and tablets are accelerating. As a result, an enormous amount of signals that cannot be compared with the conventional system flows through the packet communication path.
In packet transfer control devices (for example, EPC P-GW: Packet data network Gateway or S-GW: Serving Gateway), QCI (Quality Class Identifier), MBR (Maximum Bit Rate), G (R) By setting parameters such as QoS, QoS (Quality of Service) is controlled for each packet. However, since the network bandwidth of the entire LTE / EPC varies with time depending on the temporal variation of the traffic volume, it is difficult for the packet transfer control device to detect the timing of network congestion. Therefore, conventionally, by using a statistical method, the day of the week and the time zone in which the network is congested is examined, and the QoS parameter setting for a specific packet is changed when the day of the week or time zone information is applicable ( In particular, attempts have been made to avoid congestion by lowering the priority of QCI or narrowing down MBR and GBR.
However, such control cannot handle cases where traffic changes significantly or increases compared to statistical values due to sudden events, popular content, or new use by heavy users. There was a problem. As a result, there has been a problem relating to quality of experience (QoE) degradation, such as, for example, a very long content download time, or, in the worst case, the screen freezes on the terminal or the sound is interrupted.
Furthermore, in the future, when it starts as a real-time communication service such as high-quality VoIP and high-resolution videophone using LTE / EPC packet communication path, when the network is congested, the terminal will be used at the time of voice call by VoIP. There is a risk that problems related to deterioration of QoE (Quality of Experience) on the terminal side may occur, such as sound being interrupted or video being disturbed or frozen at the terminal during a videophone call.
Patent Document 1 is cited as a document related to the present invention. Patent Document 1 describes packet transfer control for realizing fair bandwidth allocation for each IP flow on an IP network when the backbone line is congested.

Japanese Patent Laid-Open No. 2004-320452

The present invention has been made in view of such a situation, and a problem to be solved by the present invention is to suppress occurrence of temporary interruption of packet transfer due to congestion in a packet communication network. .

In order to solve the above-mentioned problem, the present invention has, as one aspect thereof, when a packet is transferred from one of two nodes that have established a packet communication path to each other according to detection of occurrence of congestion. Provided is a packet transfer control system characterized in that, among packets transferred via a packet communication path, the bit rate of a packet carrying either voice or video is changed and transferred.
In another aspect of the present invention, when a packet is transferred from one of two nodes that have established a packet communication path between each other to the other, the packet communication path is passed through the packet communication path in response to detection of occurrence of congestion. The packet transfer control method is characterized by changing the bit rate of a packet carrying either voice or video among the packets transferred in this manner.

According to the present invention, it is possible to avoid a temporary interruption of packet transfer by changing the bit rate of a packet that carries either voice or video.

FIG. 1 is a block diagram of a communication system 100 according to the first embodiment of the present invention.
FIG. 2 is a block diagram showing a configuration of the packet transfer control device 190.
FIG. 3 is a block diagram showing the configuration of the transcoder 220.
FIG. 4 is a block diagram showing the configuration of the packet transfer control device 190 according to the second embodiment of the present invention.
FIG. 5 is a block diagram showing a configuration of portable terminal 170_1 according to the second embodiment of the present invention.

A communication system 100 according to a first embodiment of the present invention will be described with reference to FIG. Mobile network 150 is typically a mobile LTE / EPC packet network. The packet transfer control device 190 is a P-GW (Packet data network Gateway), an S-GW (Serving Gateway), or both. The mobile terminals 170_1 and 170_2 are so-called Galapagos mobiles, smartphones, and tablets, for example. Now, it is assumed that the user A of the mobile terminal 170_1 and the user B of the mobile terminal 170_2 are communicating within the same e-NodeB device 194. Here, in order to simplify the explanation, the number of users is two, but it goes without saying that the same configuration can be used for both one and three or more users.
In FIG. 1, a user A uses a portable terminal 170_1 to perform VoIP voice communication with a partner terminal (not shown) via a partner network (not shown) via the mobile network 150 and the IMS network 130. To do. In addition, a configuration in which the user B downloads Web content from the Web server using the mobile terminal 170_2 during the same time period is illustrated. Therefore, the packet transfer control device 190 performs packet transfer control for the packet communication path between the mobile terminal 170_1 and the SIP server 110, and packet transfer control for the packet communication path between the mobile terminal 170_2 and the Web server 145. Will be performed in parallel. A TV phone may be used in place of the voice communication (voice call), but in FIG.
In the present embodiment, as an example of the congestion detection method, a method of detecting congestion by receiving congestion information by ECN (Explicit Congestion Notification) from a terminal is used. That is, when the eNodeB device 194 detects a congestion state in the wireless network, the eNodeB device 194 sets a predetermined value in the ECN field of the IP header portion of the downstream packet from the eNodeB device to the mobile terminal, and sends it to the mobile terminal. When the mobile terminal detects that the ECN field of the IP header portion has a predetermined value in the packet received from the eNodeB device, the mobile terminal transmits an ECN field of the IP header portion of the uplink packet from the mobile terminal to the packet transfer control device. By establishing a predetermined value, the packet transfer control device is notified of the congestion state. As a method for detecting congestion, another method may be used as in the second embodiment described later.
In FIG. 1, when the portable terminal 170_1 sends out the IP address and RTP port number of the partner terminal from the portable terminal 170_1 as a voice call connection request, it passes through the eNodeB device 194 and the packet transfer control device 190, and the IMS ( It is transferred to at least one of the SIP server 110 and the PCRF (Policy and Charging Rules Function) device 191 disposed in the IP Multimedia Subsystem (IP) network 130. Further, the mobile terminal 170_1 adds at least one parameter among parameters such as voice call traffic, desired QoS class, MBR (Maximum Bit Rate), GBR (Guaranted Bit Rate), and the like, via the packet transfer control device 190. It is also possible to notify at least one of the SIP server 110 and the PCRF device 191.
The SIP server 110 receives a connection request signal for a voice call, sends a connection request to a partner terminal (not shown) via a partner network (not shown), and receives an Ack signal from the partner terminal. Then, the Ack signal is transmitted to the mobile terminal 170_1 via the packet transfer control device 190 and the eNodeB device 194, and is received by the mobile terminal 170_1, whereby a control signal for voice call is exchanged. Here, not only the IP address and RTP port number of the mobile terminal 170_1 but also at least one of the parameters of voice call traffic, desired QoS class, MBR (Maximum Bit Rate), GBR (Guaranteed Bit Rate) from the counterpart terminal. Can also be sent out. These parameters can be transmitted not only to the SIP server 110 but also to the PCRF device 191.
The PCRF device 191 inputs the voice call traffic, the IP address of the portable terminal 170_1, and the port number from the packet transfer control device 190 for at least one of the upstream and downstream directions. If necessary, parameters such as a desired QoS class, MBR (Maximum Bit Rate), GBR (Guaranteed Bit Rate), and the like are also input from the packet transfer control device 190.
Furthermore, the PCRF device 191 identifies a user from the IP address of the mobile terminal, and reads user profile information from the user database owned by the PCRF device 191. Here, the user profile information includes, for example, user contract information. Here, as user contract information, for example, whether it is a Premier member (a member who is not downgraded in principle even when there is network congestion) or a standard member (a member who is downgraded in principle when there is network congestion) Information such as the model name of the terminal to be used and the screen resolution of the terminal is used, but other information such as the upper limit value of the packet data amount and the capability information of the terminal can also be used.
Next, the PCRF device 191 generates parameters for QoS control based on the user profile information and the QoS information. The parameter for QoS control is at least one of QCI (Quality Class Identifier) which is a value for identifying a QoS class, ARP (Allocation and Retention Priority) indicating the priority of resource reservation and retention, MBR, and GBR. . Here, MBR and GBR are used as they are when received from the packet transfer control device 190, and are generated by the PCRF device 191 when there is no reception. The PCRF device 191 generates at least one of these four types of parameters for each of the uplink direction and the downlink direction, and outputs them to the packet transfer control device 190. For the mobile terminal 170_1, the user profile is “Premier Member”, downgrade is not permitted when the network is congested, and the traffic is a voice call. For example, QCI = 1 (Conversational Voice), ARP = 2, GBR = 12.2 kbps, MBR = 22.8 kbps are set for both uplink and downlink. Here, as an example, it is assumed that the AMR-NB audio codec is used in the mobile terminal, and the above parameter values are used. As another configuration, an AMR-WB audio codec can be used. In this case, the value of GBR can be changed.
Next, the portable terminal 170_2 designates the URL of the Web server 145 and sends a connection request. When the connection request is transferred to the Web server 145 via the eNodeB device 194 and the packet transfer control device 190, downloading of the desired content data from the Web server is started. At this time, the packet transfer control device 190 can also send the PCRF device 191 with additional parameters such as Web traffic, desired QoS class, MBR, and GBR.
In addition to the IP address and port number of the mobile terminal, the PCRF device 191 can provide Web traffic, desired QoS class, MBR (Maximum Bit Rate), GBR (Guaranteed Bit) to the user B using the mobile terminal 170_2, if necessary. Parameters such as “Rate” are input from the packet transfer control device 190. User B user profile information is read from the user database, and parameters for QoS control are generated. Specifically, they are QCI (Quality Class Identifier) which is a value for identifying the QoS class, ARP (Allocation and Retention Priority) indicating the priority of resource reservation and retention, MBR, and GBR. Here, the MBR and GBR are used as they are when received from the packet transfer control device 190, and are generated by the PCRF device 191 when there is no reception. The PCRF device 191 generates at least one of these four types of parameters in the downlink direction and outputs the generated parameters to the packet transfer control device 190. For the mobile terminal 170_2, since the user profile is “standard member”, downgrade is permitted at the time of network congestion, and because it is Web traffic, these parameter values in the downlink direction are, for example, QCI = 6 (TCP-based www), ARP = 6, GBR = 512 kbps, MBR = 1 Mbps.
Next, the configuration of the packet transfer control device 190 will be described with reference to FIG. FIG. 2 is a block diagram showing the configuration of the packet transfer control device 190. In the figure, the control unit 211 relays a control signal from the mobile terminal 170_1 to the SIP server 110, and relays a control signal and an Ack signal from the SIP server 110 to the mobile terminal 170_1. In addition, a connection request is received from the portable terminal 170_2, and a control signal is exchanged with the Web server 145. Further, at least one of four types of parameters, QCI, ARP, MBR, and GBR, is input from the PCRF device 191 for each traffic data. Here, in this embodiment, since two types of traffic, that is, voice call traffic and Web content download data traffic, are generated, at least one of four types of parameters for each of the uplink direction and the downlink direction of the voice call traffic is generated. , And at least one of four types of parameters for the downlink direction of the download data traffic is input from the PCRF device 191. The control unit 211 outputs these parameters to the transfer control unit 188, and the transfer control unit 188 controls packet transfer to the packet transfer unit 176 according to the input QoS parameters.
The congestion detection unit 200 checks an ECN (Explicit Congestion Notification) field in the IP header for uplink packets transmitted from the mobile terminal 170_1 and the mobile terminal 170_2 via the packet transfer unit 176. When the ECN field has a predetermined value, it detects that the downlink direction from the eNodeB device 194 to the mobile terminal is in a congestion state, outputs downlink congestion detection information to the control unit 211, and the control unit 211 The congestion detection information is sent to the PCRF device 191 shown in FIG.
When the congestion detection information is input from the control unit 211 in FIG. 2, the PCRF device 191 in FIG. 1 receives at least user profile information and QoS parameters for each of the mobile terminal 170_1 and mobile terminal 170_2 currently connected to the eNodeB device 194. Check one side. Here, the case where both are checked is shown. According to the user profile information, the mobile terminal 170_1 is a “premier member” and recognizes that downgrade at the time of network congestion is not permitted. As described above, the QoS parameters of the portable terminal 170_1 are QCI = 1 (Conversational Voice), ARP = 2, GBR = 12.2 kbps, and MBR = 22.8 kbps for both uplink and downlink. On the other hand, according to the user profile, the mobile terminal 170_2 is a “standard member” and recognizes that downgrade is permitted when the network is congested. As described above, the QoS parameter is set to the downlink direction, QCI = 6 ( TCP-based www), ARP = 6, MBR = 1 Mbps. Therefore, by comparing the user profile information and the QoS parameters, in particular, QCI and ARP, the PCRF device 191 does not change the QoS parameter for the portable terminal 170_1, but changes the QoS parameter for the portable terminal 170_2. Judgment and change so. Here, as an example, the mobile terminal 170_2 is changed to QCI = 6 (TCP-based www), ARP = 6, GBR = 256 kbps, and MBR = 512 bps. Then, the changed QoS parameter is sent to the packet transfer control device 190. Specifically, the data is sent to the transfer control unit 188 via the control unit 211 of FIG.
Returning to FIG. 2, the transfer control unit 188 inputs the changed QoS parameter from the PCRF device 191 via the control unit 211. Then, the mobile terminal 170_1 recognizes that the QoS parameter has not been changed, and no change is made to the transfer control of packets transmitted and received from the mobile terminal 170_1. On the other hand, the mobile terminal 170_2 recognizes that the QoS parameter has been changed, and for the downstream packet transmitted to the mobile terminal 170_2, the changed QoS parameter is transmitted to the transcoder unit 220 and the packet transfer unit. Notification to the unit 176.
Next, the configuration of the transcoder unit 220 will be described with reference to FIG. The transcoder unit 220 includes demultiplexing / multiplexing units 280_1 and 280_2, an image transcoder 281, an audio transcoder 282, an audio transcoder 283, and a text transcoder 284. The demultiplexing / multiplexing unit 280_1 receives the changed QoS parameter from the transfer control unit 188 and distributes it to each transcoder. Downstream and upstream packets are input from the packet transfer control device 190, the media streams are separated, and output to the transcoders. The image transcoder 281 transcodes the video stream. The audio transcoder 282 and the audio transcoder 283 are responsible for different frequency bands, and both transcode the audio stream. Note that the audio transcoder 282 and the audio transcoder 283 may be integrated.
The instruction from the transfer control device 188 is to change the QoS parameter of the downstream packet directed to the mobile terminal 170_2, in particular, to reduce the GBR to 256 kbps and the MBR to 512 kbps. For this purpose, at least one of an audio stream, a video stream, and text information is extracted from the downstream packet sent to the mobile terminal 170_2, and the stream is converted so that the total bit rate satisfies GBR = 256 kbps and MBR = 512 kbps. To do.
Here, as an example, an example in which a video stream and an audio stream having a high bit rate are extracted and converted will be described. The original video stream is H.264. Assume that encoding is performed at an average bit rate of 512 kbps by the H.264 video codec. This is the same as H. 264 is transcoded by the image transcoder 281 so that the average bit rate is reduced to 200 kbps, which is lower than the setting value of GBR after the change of 256 kbps. The H.264 stream is output to the demultiplexing / multiplexing unit 280_2. Further, assuming that the original audio stream is encoded at 128 kbps by MPEG-4 AAC, the audio stream is transcoded at 48 kbps by the audio transcoder 282 and output to the demultiplexing / multiplexing unit 280_2. The text information is passed through by the transcoder and output to the demultiplexing / multiplexing unit 280_2. Note that the audio transcoder 282 is not used because the audio content that is the target of the audio transcoder 282 is not included in the Web content. The demultiplexing / multiplexing unit 280_2 receives outputs from the image transcoder 281, the audio transcoder 283, and the text transcoder 284, stores them in a packet, and outputs them to the packet transfer unit 176 in FIG.
Returning to FIG. 2, the packet transfer unit 176 performs QCI = 1 (conversational voice), ARP = 2, GBR = 12.2 kbps, MBR = 2.22 for the uplink and downlink packets for the mobile terminal 170_1. The packet is transferred preferentially without changing at 8 kbps. On the other hand, QCI = 6 (TCP-based www) and ARP = 6 remain as they are for the downstream packet for the mobile terminal 170_2, but GBR and MBR are changed to GBR = 256 kbps and MBR = 512 bps. Then, the packet that is the output of the transcoder 220 is transferred.
This is the end of the description of the present embodiment, but various modifications can be made to the present embodiment. In the above description, the case of performing a voice call and downloading application software has been described, but real-time communication and data download can be used for other services with the same configuration. For example, the same configuration can be applied to a TV phone and content download.
Although congestion detection uses ECN information, other information can also be used. Further, the packet transfer control device 190 can directly input the congestion information from the eNodeB device 194.
Although the congestion detection unit 200 and the transcoder 220 are built in the packet transfer control device 190, they may be external devices. Further, the function of the PCRF device 191 can be built in the packet transfer device 190.
The mobile network 150 may be a 3G network, and the packet transfer control device 190 may be an SGSN (Serving GPRS Support Node) or a GGSN (Gateway GPRS Support Node).
Next, a second embodiment of the present invention will be described. Compared with the first embodiment, the second embodiment is different in the configuration of the packet transfer control device 190 and the portable terminals 170_1 and 170_2, and the other configurations are the same as those of the communication system 100 in FIG. The packet transfer control device 190 and the portable terminals 170_1 and 170_2 will be mainly described. In FIG. 4, the constituent elements having the same numbers as those in FIG. 2 perform the same operations as those in FIG.
In FIG. 4, the bandwidth measuring unit 205 calculates at least one bandwidth of the network to which the mobile terminal 170_1 and the mobile terminal 170_2 are connected at the time of session connection or at predetermined time intervals.
The bandwidth measuring unit 205 uses the transmission packet from the packet transfer unit 176 and the reply packet from the mobile terminal 170 to the upstream and downstream bands for the network connected to the mobile terminal 170. At least one of them is measured. In the present embodiment, a configuration in the case of measuring both upstream and downstream bands will be described. First, the bandwidth measuring unit 205 instructs the packet transfer unit 176 in FIG. 3 to transmit a probe packet including two or more predetermined packets having different data sizes at a predetermined timing. In accordance with the instruction, the packet transfer unit 176 sends probe packets to the portable terminal 170_1 or the portable terminal 170_2 at a timing when the instruction is received, and continuously transmits in a predetermined order in time. The order in which a plurality of packets, which are probe packets, are transmitted is a predetermined order. For example, packets from a small data size to a large data size are sequentially transmitted. Further, the time interval between the packet and the next packet is a predetermined time interval. Here, for example, RTP / UDP / IP is used as the protocol.
Next, the packet transfer unit 176 receives a reply packet from the portable terminal 170_1 or the portable terminal 170_2 as a result of sending the plurality of packets. Hereinafter, a reply packet from the portable terminal 170_1 will be described, but a reply packet from the portable terminal 170_2 has the same configuration. Here, the reply packet includes, for example, the packet number that can be received below the threshold with respect to the differential delay, the data size of the packet, the time when the packet was transmitted from the packet transfer unit 176, in the mobile terminal 170_1, Information such as the time when the packet is received by the mobile terminal is included.
The packet transfer unit 176, from the reply signal received from the mobile terminal 170_1, indicates the packet number that the mobile terminal 170_1 has received below the delay difference threshold, the transmission time from the mobile terminal 170_1, and the reception time at the mobile terminal. Information is extracted and output to the bandwidth measuring unit 205.
The bandwidth measuring unit 205 receives the above information from the packet transfer unit 176 and calculates the network bandwidth.
In portable terminal 170_1, information on the packet number that could be received within the threshold of delay difference, the data size of the packet, the transmission time of packet from packet transfer unit 176, and the reception time of the packet at portable terminal Then, the downstream band W_d is calculated according to the following Equation 1.
D (N) / W_d = R (N) -R (N-1) (Formula 1)
In Expression 1, D (N) represents the data size of the Nth packet transmitted from the packet transfer unit 176. Here, N and D (N) indicate the number and data size of a packet that can be received by the portable terminal 170_1 below the delay difference threshold value, respectively. R (N) is the reception time at the portable terminal 170_1 of the Nth packet sent from the packet transfer unit 176, and R (N-1) is the N-1th packet sent from the packet transfer unit 176. The reception time at portable terminal 170_1 is shown.
Next, the downstream bandwidth measurement value W_d is temporally smoothed by Equation 2 to calculate B (n) _d.
B (n) _d = (1-β) * B (n−1) _d + βW_d (Expression 2)
Here, B (n) _d indicates a downstream band measurement value after smoothing at the nth time, and β is a constant in a range of 0 <β <1. Note that the time direction smoothing according to Equation 2 may not be performed if unnecessary.
Next, the mobile terminal 170_1 sends a plurality of specific packets to the packet transfer control device 190 in a predetermined order at any timing after the connection request or when the reply signal is transmitted. Thus, the packet transfer control device 190 measures the upstream band. Here, the plurality of packets indicates two or more packets. The sending order is a predetermined order. For example, packets are sent in order from a packet having a small data size to a packet having a large data size. Further, the time interval between the packet and the next packet is a predetermined time interval. Here, for example, RTP / UDP / IP is used as the protocol.
When the bandwidth measuring unit 205 receives each of the plurality of probe packets transmitted from the portable terminal 170_1 in FIG. 5 from the packet transfer unit 176, the bandwidth measuring unit 205 measures the delay time T (n) for each packet using Equation 3.
T (n) = R (n) -S (n) (Formula 3)
Here, T (n), R (n), and S (n) indicate the delay time of the nth packet, the reception time of the nth packet, and the transmission time of the nth packet, respectively.
Further, the bandwidth measuring unit 205 calculates a delay difference τ (n) between the packets using Equation 4.
τ (n) = T (n) −T (n−1) (Formula 4)
Here, τ (n) represents the delay difference of the nth packet.
Next, using τ (n), it is determined whether or not the delay difference exceeds a predetermined threshold value. If τ (n) ≧ Th3, it is determined that the delay difference has exceeded the threshold value in the nth packet. Here, Th3 is a predetermined threshold value.
Based on the determination result and the probe packet received from the mobile terminal 170_1, the bandwidth measuring unit 205 determines the number of the packet that can be received below the delay difference threshold, the data size of the packet, and the mobile terminal of the packet. And the reception time information of the packet at the packet transfer unit 176, and the upstream bandwidth W_u is calculated according to the following equation 5.
D (M) / W_u = P (M) -P (M-1) (Formula 5)
In Equation 5, D (M) represents the data size of the Mth packet transmitted from the mobile terminal 170_1. M and D (M) respectively indicate the number and data size of a packet that can be received by the packet transfer unit 176 below the delay difference threshold value. P (M) is the reception time at the packet transfer unit 176 of the Mth packet sent from the mobile terminal 170_1, and P (M-1) is the packet of the M-1th packet sent from the mobile terminal 170_1. The reception time at the transfer unit 176 is shown.
Next, the bandwidth measurement value W_u in the upstream direction is temporally smoothed by the following equation 6 to calculate B (n) _u.
B (n) _u = (1-β) * B (n−1) _u + βW_u (Expression 6)
The packet transfer unit 176 sends information necessary for network bandwidth measurement to the portable terminal 170 only at the time of session connection or at predetermined time intervals based on the time of session connection and session connection, for example. A response signal is received from the mobile terminal.
The bandwidth measuring unit 205 calculates B (n) _d and B (n) _u for each predetermined time interval, for example, for each packet communication path for which transfer control is performed by the packet transfer control device 190. These are output to the congestion detection unit 210.
The congestion detection unit 210 performs the following (1)-(4) to detect congestion.
(1) The bandwidth calculation value B (n) _d in the downlink direction calculated between the mobile terminal 170_1 and the GBR + α in the downlink direction of the voice call by the mobile terminal 170_1 are compared. α is a margin, and a predetermined value is used.
When this comparison result is B (n) _d ≧ GBR + α, the congestion detection unit 210 determines that congestion has not occurred in the downstream path of the mobile terminal 170_1. Then, the congestion detection unit 210 notifies the PCRF device 191 in FIG. 1 through the control unit 211 in FIG. 2 that the QoS parameter is not changed.
On the other hand, if the comparison result is B (n) _d <GBR + α, the congestion detection unit 210 determines that congestion has occurred in the downstream path of the mobile terminal 170_1, and uses this as congestion information to indicate the PCRF device. 191 is notified.
(2) The bandwidth calculation value B (n) _u in the uplink direction calculated between the mobile terminal 170_1 and the GBR + α ′ in the uplink direction of the voice call by the mobile terminal 170_1 are compared. α ′ is a margin, and a predetermined value is used. Α ′ = α may also be used.
When the comparison result is B (n) _u ≧ GBR + α ′, the congestion detection unit 210 determines that no congestion has occurred in the uplink path of the mobile terminal 170_1. Then, the congestion detection unit 210 notifies the PCRF device 191 in FIG. 1 through the control unit 211 in FIG. 2 that the QoS parameter is not changed.
On the other hand, if the comparison result is B (n) _u <GBR + α ′, the congestion detection unit 210 determines that congestion has occurred in the uplink path of the mobile terminal 170_1, and uses that as the congestion information to indicate that the PCRF Notify the device 191.
(3) The downlink bandwidth calculation value B (n) _d calculated with the mobile terminal 170_2 is compared with the GBR + γ related to Web content by the mobile terminal 170_2. γ is a margin, and a predetermined value is used. If this comparison result is B (n) _d <GBR + γ, the congestion detection unit 210 determines that congestion has occurred in the downstream path with respect to the mobile terminal 170_2, and informs the PCRF device 191 of the fact as congestion information. Notice.
Note that here, the determination on the occurrence of congestion in the upward direction of the mobile terminal 170_2 is omitted. This is because the portable terminal 170_2 is downloading web content, and therefore requires only a negligible bandwidth in the upstream direction.
Returning to FIG. 1, when the congestion detection information is input from the congestion detection unit 210 of FIG. 3, the PCRF device 191 checks at least one of the user profile information and the QoS parameter for each of the mobile terminal 170_1 and the mobile terminal 170_2. As described above, the QoS parameters for the portable terminal 170_1 are QCI = 1 (Conversational Voice), ARP = 2, GBR = 12.2 kbps, MBR = 22.8 kbps for both uplink and downlink, and the QoS parameters for the portable terminal 170_2. As described above, the downlink direction, QCI = 6 (TCP-based www), ARP = 6, and MBR = 1 Mbps. Among these parameters, in particular, when QCI and ARP are compared, it can be seen that the portable terminal 170_1 has priority over the portable terminal 170_2. Accordingly, the PCRF device 191 further refers to the user profile information, recognizes that the mobile terminal 170_1 is a “premier member” and does not allow downgrade during network congestion, and does not change the QoS parameters for the mobile terminal 170_1. . On the other hand, the mobile terminal 170_2 is a “standard member”, recognizes that downgrade is permitted when the network is congested, and changes the QoS parameter for the mobile terminal 170_2. Here, as an example, the mobile terminal 170_2 is changed to QCI = 6 (TCP-based www), ARP = 6, GBR = 256 kbps, and MBR = 512 bps. Then, the changed QoS parameter is sent to the packet transfer control device 190 and the transcoder 220. Specifically, the data is sent to the transfer control unit 188 and the transcoder 220 via the control unit 211 of FIG. Then, as described in the first embodiment, the transcoder 220 reduces the bit rate of the video stream and the audio stream.
FIG. 5 is a block diagram illustrating a configuration of the mobile terminal 170_1. Since the portable terminal 170_2 has the same configuration, the description thereof is omitted. The mobile terminal 170_1 of the present embodiment is characterized in that it includes a delay difference determination unit 255. In FIG. 5, a packet transmitting / receiving unit 250 generates a reply packet for the received probe packet and sends it to the network. Here, the reply packet is generated as follows, for example.
The packet transmission / reception unit 250 receives each of the plurality of probe packets transmitted from the packet transmission / reception unit 176 of FIG. 2 and outputs it to the delay difference determination unit 255.
The delay difference determination unit 255 measures the delay time T (n) for each packet using Equation 7.
T (n) = R (n) -S (n) (Formula 7)
Here, T (n), R (n), and S (n) indicate the delay time of the nth packet, the reception time of the nth packet, and the transmission time of the nth packet, respectively.
Further, the delay difference τ (n) between each packet is calculated by Equation 8.
τ (n) = T (n) −T (n−1) (Equation 8)
Here, τ (n) represents the delay difference of the nth packet.
Next, using τ (n), it is determined whether or not the delay difference exceeds a predetermined threshold value. If τ (n) ≧ Th3, it is determined that the delay difference has exceeded the threshold value in the nth packet. Here, Th3 is a predetermined threshold value. Then, the packet number N immediately after the delay difference exceeds the threshold value is output to the packet transmitting / receiving unit 250.
The packet transmitting / receiving unit 250 receives the packet number N from the delay difference determining unit 255, the packet number N immediately after the delay difference exceeds the threshold value, the data size of the Nth packet, and the (N-1) th packet. 1 is stored in the payload of the reply packet, and then transmitted to the packet transfer control device 190 via the eNodeB device 194 in FIG.
Here, the threshold value Th3 may be determined in advance, or may be determined each time after looking at a series of values of τ (n).
Also, other methods can be used as the discrimination method. For example, T (n) may be compared with a threshold value, and n when the threshold value is exceeded may be set to N.
In FIG. 5, a voice codec 253 is used during a voice call. The text decoder 251 and the image codec 252 are used for decoding Web contents in which text and images are mixed. The text decoder 251 and the image codec 252 decode the text and images and output them to the screen display unit 256. The screen display unit 256 displays on the mobile terminal display. To do.
The operation when the communication system 100 according to the second embodiment detects congestion is as follows.
(1) The packet transfer unit 176 sends a probe packet to the portable terminal 170_1 in accordance with an instruction from the bandwidth measuring unit 205.
(2) When receiving the probe packet, the portable terminal 170_1 operates as follows.
(2.1) Upon receiving the probe packet, the portable terminal 170_1 receives the packet number N immediately after the delay difference exceeds the threshold, the data size of the Nth packet, and the data size of the N-1th packet. Then, a reply packet in which the reception time and transmission time of each packet is stored in the payload is generated, and the reply packet is sent to the packet transfer control device 190 via the eNodeB device 194.
(2.2) The portable terminal 170_1 transmits a probe packet to the packet transfer control device 190 via the eNodeB device 194. The sending order of the reply packet and the probe packet may be switched. Further, one of the probe packets may be used as a reply packet.
(3) When the reply packet and the probe packet are received from the portable terminal 170_1, the packet transfer control device 190 operates as follows.
(3.1) The bandwidth measuring unit 205 stores the value stored in the received reply packet, that is, the packet number N immediately after the delay difference exceeds the threshold, the data size of the Nth packet, N− The downlink bandwidth W_d is calculated by applying the data size of the first packet, the reception time of each packet, and the transmission time to Equation 1.
(3.2) The band measurement unit 205 calculates the smooth value B (n) _d by applying the calculated downstream band W_d to Equation 2.
(3.3) The bandwidth measuring unit 205 receives from the received probe packet the number of the packet that can be received within the delay difference threshold value, the data size of the packet, the transmission time of the packet from the mobile terminal, the packet Information of the reception time at the packet transfer unit 176 is obtained, and the upstream band W_u is calculated by applying the information to Expression 5.
(3.4) The band measuring unit 205 applies the calculated upstream band W_u to Equation 6 to obtain the smoothed value B (n) _u. It should be noted that the steps (3.1) and (3.2) and the steps (3.3) and (3.4) may be performed in reverse order or in parallel.
(3.5) The congestion detection unit 210 determines whether or not congestion is detected based on B (n) _d and B (n) _u.
(3.6) The operation after detecting congestion is the same as that of the first embodiment.
This is the end of the description of the configuration of the present invention, but various modifications are possible.
Another algorithm can be used as the band measurement algorithm in the band measurement unit 205 of FIG. Although the band is calculated based on the response signal from the portable terminal, it is also possible to measure the delay amount with the portable terminal and calculate the band based on this.
Note that it is also possible to use a method of estimating a band using a response signal from a portable terminal without using a probe packet, instead of measuring a band by sending a probe packet for band measurement from a packet transfer unit. In this case, the delay difference determination unit 255 in FIG. 4 is not necessary.
In this embodiment, the bandwidth measuring unit 205 and the congestion detecting unit 210 are built in the packet transfer control device 190, but at least one of them can be an external device.
One effect of the first and second embodiments will be described. When the bandwidth of the LTE / EPC network varies temporally depending on the variation in traffic volume, parameter values such as QCI (Quality Class Identifier), MBR (Maximum Bit Rate), GBR (Guaranteed Bit Rate), etc. According to the packet transfer control technology that performs transfer control based on the setting of the terminal, as a result of following a large fluctuation, the sound is interrupted at the terminal during a voice call using VoIP, or the video is disturbed at the terminal during a videophone call. Or there is a risk of freezing.
According to the first and second embodiments, the presence / absence of congestion in the network is determined using a method such as estimating the network bandwidth based on the response signal from the mobile terminal and the amount of delay, and the congestion. When the occurrence is detected, for example, a packet having a high priority given by the QCI value or the ARP value is preferentially transferred, while a packet having a low priority is reduced by the transcoder to reduce the amount of data. Transfer control is performed so as to be within the specified bandwidth. For this reason, it can avoid reaching the above-mentioned situation.
This application claims the priority on the basis of Japanese application Japanese Patent Application No. 2012-262972 for which it applied on November 30, 2012, and takes in those the indications of all here.

Claims (10)

  1. When transferring packets from one of the two nodes that have established a packet communication path between each other to the other, in response to detection of congestion occurrence, of the packets transferred through the packet communication path, audio and video A packet transfer control system, wherein the bit rate of a packet carrying one of the packets is changed and transferred.
  2. Means for comparing a QoS parameter, which is a parameter for QoS (Quality of Service) control of a packet communication path, between a plurality of different packet communication paths that are currently subject to packet transfer control;
    Means for changing a QoS parameter of a packet transferred through a part of the plurality of packet communication paths according to a result of the comparison;
    The packet transfer control system according to claim 1, further comprising means for changing a bit rate of a corresponding packet based on the changed QoS parameter.
  3. The QoS parameters include a QCI (Quality Class Identifier) that is a value for identifying a QoS class, an ARP (Allocation and Retention Priority) indicating a priority for securing and retaining resources, an MBR (Maximum Bit Rate), and a GBR (Guarante Guate). 3. The packet transfer control system according to claim 1, wherein the packet transfer control system is at least one of the following.
  4. The packet transfer control system according to any one of claims 1 to 3, wherein occurrence of congestion is detected based on ECN (Explicit Congestion Notification) stored in the packet.
  5. 5. The probe packet is transmitted to a terminal that is one of two nodes that establish a packet communication path, and occurrence of congestion is detected based on a response to the probe packet. The packet transfer control system according to any one of the above.
  6. When transferring packets from one of the two nodes that have established a packet communication path between each other to the other, in response to detection of congestion occurrence, of the packets transferred through the packet communication path, audio and video A packet transfer control method, wherein the bit rate of a packet carrying one of the packets is changed and transferred.
  7. A QoS parameter that is a parameter for QoS (Quality of Service) control of a packet communication path is compared between a plurality of different packet communication paths that are currently subject to packet transfer control,
    According to a result of the comparison, a QoS parameter of a packet transferred through a part of the plurality of packet communication paths is changed,
    The packet transfer control method according to claim 6, wherein the bit rate of the corresponding packet is changed based on the changed QoS parameter.
  8. The QoS parameters include a QCI (Quality Class Identifier) that is a value for identifying a QoS class, an ARP (Allocation and Retention Priority) indicating a priority for securing and retaining resources, an MBR (Maximum Bit Rate), and a GBR (Guarante Guate). The packet transfer control method according to claim 6, wherein the packet transfer control method is at least one of the following.
  9. The packet transfer control method according to any one of claims 6 to 8, wherein the occurrence of congestion is detected based on ECN (Explicit Congestion Notification) stored in the packet.
  10. 10. The probe packet is transmitted to a terminal that is one of two nodes that establish a packet communication path, and occurrence of congestion is detected based on a response to the probe packet. The packet transfer control method according to any one of the above.
PCT/JP2013/079329 2012-11-30 2013-10-23 Packet transfer control system and method WO2014083994A1 (en)

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